Chemical baths used for cleaning surfaces of materials such as metals and semiconductors are necessarily low pH or high pH liquids that are often corrosive and highly reactive with many of the materials used to form the housing for the baths. Use of such chemical bath liquids usually requires that the bath housing be constructed of a material that is relatively inert to, or that resists chemical reaction with, a chemical bath liquid in a static bath and, preferably, in a changing environment in which vibrations or waves are introduced and maintained in the liquid. A material such as stainless steel or aluminum will promptly begin to react with and corrode in such a chemical bath liquid, and the life of such a solid material as part of the bath housing is therefore limited. Further, the ability of a conventional bath housing material to transmit or re-radiate vibrations that are intentionally introduced at the bath housing, for transmission into and through the chemical bath liquid, is often limited.
A method of electrically bonding electrical conductors to materials such as polyetheretherketone ("PEEK") is disclosed by Felix et at in U.S. Pat. No. 4,871,412.
Processes for forming high temperature, solvent-resistant, creep-resistant and/or moisture-resistant articles from polymeric materials such as PEEK is disclosed in U.S. Pat. No. 5,057,600, issued to Beck et at, in U.S. Pat. No. 5,419,208, issued to Schick, in U.S. Pat. No. 5,433,530, issued to Waskdewicz, in U.S. Pat. No. 5,454,693, issued to Aubry et at, in U.S. Pat. No. 5,455,201, issued to Gotoh et al, in U.S. Pat. No. 5,462,408, issued to Coffy, in U.S. Pat. No. 5,478,372, issued to Stark, in U.S. Pat. No. 5,521,000, issued to Owens, and in U.S. Pat. No. 5,549,276, issued to Pittman et al. Processing for a composite including polyphenylene sulfide ("PPS") is disclosed by Roberts et al in U.S. Pat. No. 5,583,583.
The inventions disclosed in these patents take advantage of the relative inertness of articles made of materials such as PEEK, poly-amide-imide ("PAI") and PPS in relatively static environments in which exposure to chemicals, to high temperatures, to high stresses and to similar conditions is more-or-less unchanging and predictable. These predictable and unchanging conditions are not present in a semiconductor wafer chemical bath in which the wafers are exposed to a sequence of high pH and low pH chemicals and to intermittent radiation at frequencies of tens to hundreds of kilohertz.
What is needed is a chemical bath housing material that (1) resists chemical breakdown, such as corrosion or dissociation, by a low pH and/or high pH chemical bath liquid to which the housing material is exposed and (2) permits re-radiation into the chemical bath liquid of vibrations in a frequency band including at least the range 20-750 kHz that are introduced intermittently into the chemical bath without substantial degradation of the definition or other characteristics of the vibrations.